In wireless communication systems, user terminals (UTs) and access points or base stations (BSs) exchange data over an air interface. The BSs may be geographically distributed, e.g., into cells. The UTs and BSs establish an air interface through an exchange of wireless communication signals. The process of exchanging signals to establish an air interface may be referred to as “handshaking.” The handshaking process may include a UT requesting a resource, such as a traffic channel (TCH), and a BS determining a TCH assignment for the UT, and responding to the request with the channel assignment.
One handshaking technique involves assigning a TCH stream on a conventional channel resource using a random access channel (RACH). The RACH may be a channel, e.g., a control channel, which is not specifically assigned to any particular UT, and may be accessed by a UT seeking a TCH assignment on a BS. This technique traditionally requires the handshaking to complete in a single frame. For example, a random access signal (RA) may be sent on the uplink of a frame and an access assignment signal (AA) is sent on the downlink of the same frame. The AA will typically indicate the TCH channel assignment determined by the BS. The frame may be an exchange period defined in a wireless communication protocol.
Although this technique is relatively simple, it is difficult to implement in a distributed base station architecture. In a distributed base station architecture, the processing may not all be performed with a single processor. A general purpose processor (GPP) that is typically not a real-time processor may not have the capability to meet the real-time requirements of making an assignment of available resources and transmitting the assignment in the same frame as the resource request.
In a distributed architecture, a combination of one or more GPPs and application specific processors (ASPs), e.g., digital signal processors (DSPs), application specific integrated circuits (ASICs), etc., is generally used. An ASP may control a set or subset of communication resources, for example, spatial channels. To perform resource assignments, a GPP may need to engage in interprocessor communication with one or more ASPs. The interprocessor communication may be difficult to perform in a manner consistent with the real-time requirements of transmitting a channel assignment on the downlink of a frame where the request was received on the uplink.